CT or ct may refer to:

In arts and media

* ''c't'' (''Computer Technik''), a German computer magazine * List of Red vs. Blue characters#C.T., Freelancer Agent Connecticut (C.T.), a fictional character in the web series ''Red vs. Blue'' * Christianity Today, an American evangelical Christian magazine

Businesses and organizations

* CT Corp, an Indonesian conglomerate * CT Corporation, an umbrella brand for two businesses: CT Corporation and CT Liena * C/T Group, formerly Crosby Textor Group, social research and political polling company * Canadian Tire, a Canadian company engaged in retailing, financial services and petroleum * Calgary Transit, the public transit service in Calgary, Alberta, Canada * Central Trains (National Rail abbreviation), a former train operating company in the United Kingdom * Česká televize, the public television broadcaster in the Czech Republic * Community Transit, the public transit service in Snohomish County, Washington, U.S. * Comunión Tradicionalista, a former Spanish political party * CT (TV channel), a Filipino cable and satellite television network

Finance

* Centime (ct), the French for "cent", used in English in several Francophone countries * Stotinki (ст), the currency of Bulgaria

Places

* CT postcode area, for Canterbury and surrounding areas in south-eastern England * Connecticut (United States postal abbreviation) * Province of Catania (vehicle registration code), Sicily, Italy * Central African Republic (FIPS Pub 10-4 code and obsolete NATO diagram) * Canton and Enderbury Islands (obsolete ISO 3166 country code), part of the Phoenix Islands in the Pacific Ocean *Cape Town (capital city of the Western Cape, South Africa) * Ct, for "Court"; a street suffix as used in the US

Science and technology

Biology and medicine

* Haplogroup CT, Y-DNA haplogroup. * CT scan or X-ray computed tomography, a medical imaging method * Calcitonin (symbol CT), a hormone produced in the thyroid gland * Calibrated automated thrombogram (CT or CAT), a coagulation test * Cardiothoracic surgery, the field of medicine specializing in chest surgery * Chemotype (ct.), a chemically distinct entity in a plant or microorganism * Cognitive therapy, a type of psychotherapy * Connective tissue, a type of biological tissue * Chelation therapy * Chemotherapy *Cholera toxin, a toxic protein secreted by ''Vibrio cholerae'' * Threshold Cycle (C_t), see cycle of quantification/qualification * COVID-19 test

Computing

* Intel Ct, a SIMD multithreading programming model developed by Intel * Certificate Transparency, in network security

Other uses in science and technology

* CT Value, in drinking water disinfection * Threshold cycle (C_t), a measure in the cycle of quantification/qualification of a real-time polymerase chain reaction * Carat (purity) (ct), a measure of the purity of gold and platinum alloys * Carat (mass) (ct), a unit of mass used for measuring gems and pearls * Continuous-time signal, a varying quantity (a signal) whose domain is a continuum * Center tap, a wire that is connected halfway along one of the windings of a transformer, inductor or a resistor * Compliant Tower, a deepwater offshore oil platform * Convective temperature, in atmospheric science * Current transformer, a kind of transformer used in the electrical power industry

Transportation

* Lexus CT, an automobile * Honda CT series, a series of Honda bikes * Crawler-transporter, a tracked vehicle used to transport the Space Shuttle from Vehicle Assembly Building to Launch Complex 39 * Civil Air Transport (IATA code) * Training cruiser, a U.S. Navy hull classification

Other uses

* Ct, a typographic ligature * ''c. t.'' (cum tempore, Latin for "with time"), indicates that a lecture will begin a quarter-hour after the stated time; see Academic quarter (class timing), Academic quarter * Central Time Zone, a time zone in Canada, the United States, and Mexico * Coffin Texts * Conspiracy theory or theorist * Counter-terrorism * Cryptologic technician, a United States Navy enlisted rating or job specialty * Chinese Taipei, the name used by Taiwan in some international organizations due to political pressure from the People's Republic of China * ct followed by a number means the number of items contained in a cardboard (e.g. zucchini 3 ct) * Corps Turd, etymologically "Cadet in Training", member of the Glossary of Texas A&M University terms#C, Texas A&M Corps of Cadets that is not in the band